Percent Change of the Income Tax Rate in Illinois

In July 2017 the Illinois State Legislature raised the income tax rate from 3.75% to 4.95%. This change can be described two ways. “The tax rate increased by 1.2 percentage points.” or “The tax rate increased 32%.”

Percent change = change/original = 1.2/3.75 = .32 = 32%

Percent change is the primary way that we (and the media) describe change. When the data itself is a percent, it can be a bit confusing.